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Question : Dual Router setup problems
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I am trying to have a dual router setup
for the sake of having two Wan IP's and two NAT gateway's to play with
currently I have only tried this with two Linksys BEFSR41 routers
the routers both have a WAN port and 4 port switch built in
I also have 2 additional switches
NAT is turned enabled on both routers, DHCP is turned off on both routers
The Wan ports on each router have a real ip x.x.x.x
The internal Lan ports use 192.168.0.1 and 192.168.0.2, also tried 192.168.1.1 and 192.168.2.1
1.
This setup works as one would expect,
but lacks tha ability of dual LAN gateways,
and lacks the ability for lana and lanb to talk to each other locally
Wan
|
Switch
| |
RouterA RouterB
| |
LanA LanB
2.
In an attmpet to solve the problem
I connected the built in swithes with a cross over cable from port to port
I also tried a normal cable from port to uplink, and uplink to port
In either case, it causes a massive broadcast storm.
Wan
|
Switch
| |
RouterA RouterB
| | | |
| ----- |
| |
LanA LanB
3.
To see if was a problem with the builit in switched
I connected both routers to a second switch,
This also causes massive broadcast storm.
Wan
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Switch1
| |
RouterA RouterB
| | | |
| Switch2 |
| |
LanA LanB
4.
The only thing I could think of was to use a pc with dual nics
This worked, but..
Wan
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Switch1
| |
RouterA RouterB
| | | |
| Computer |
| |
LanA LanB
I know that If had 3 switches and hooked 1 to 2, 2 to 3, and 3 to 1, it is really really bad
The only thing I can figure as to why it wont work or isnt working the way I thought (2. or 3.)
is that the linksys routers also being switches see same mac address on the wan on the lan side
and that the wan port isnt really a seperate interface
so when hooked up like I want they act like switches which isnt good
Is this possible ?
Wan
|
Switch
| |
RouterA RouterB
| | | |
| --- |
| |
LanA LanB
It doenst make sense that it wouldn't, how do larger networks deal with this scenario ?
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Answer : Dual Router setup problems
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I'm going to stand firm on my assessment.
1. Why is it doing what it is doing? Spanning Tree is the root cause of the packet loops. Period. No Spanning tree running on your switches, nothing to stop the loops.
Now, I'll try to explain the rest.
WANA = 12.34.56.7
LANA = 192.168.1.1
WANB = 45.67.89.1
LANB = 192.168.2.1
Even if you connect LANA to LANB with a crossover cable, or use a 3rd switch between them, they are not on a common subnet and there is no way to put in a static route. Example.
RTRA = static route 192.168.2.0 mask 255.255.255.0 -> 192.168.2.1 <--even though it is physically connected, it is not on the same subnet and this will not work, because the only way to get to it is to go out the WAN interface
RTRB = static route 192.168.1.0 mask 255.255.255.0 -> 192.168.1.1 <-- ditto
You could add static routes pointing to the opposite WAN interface:
RTRA= static route 192.168.2.0 mask 255.255.255.0 -> 45.67.89.1 (WANB)
RTRB= static route 192.168.1.0 mask 255.255.255.0 -> 12.34.56.7 (WANA)
However, since the real routing is dependent on the upstream router, the private addresses will most likely be dropped.
If you put another router in between (your 2NIC PC in this case) with one interface in each LAN, then bingo, everything works because you can add static routes:
RTRA=static route 192.168.2.0 mask 255.255.255.0 192.168.1.2 <--address of PC NICA
RTRB=static route 192.168.1.0 mask 255.255.255.0 192.168.2.2 <--address of PC NICB
And, I will also stand firm on the fact that you cannot have dual WAN gateways working in tandem to load-balance/failover with what you have.
I will however, offer a compromise solution, though it is not something that I would recommend in a business environment. The physical setup is just as you have in situation #1.
Both routers' internal subnet is the same, but they have different IP's, i.e.
RTRA = 192.168.1.1
RTRB = 192.168.1.254
All PC's on the LAN have the same IP Subnet.
1/2 of the PC's point the default gateway to RTRA, 1/2 of the PC's point the default gateway to RTRB. There is your load-balancing.
Add a 2nd gateway to each PC pointing to the opposite RTR IP. In case one DSL line goes down, power off the respective RTR and everyone goes out the other DSL line automatically (Dead Gateway Detect takes over, but only if the original Gateway itself cannot be contacted - reason you have to power down the router). This is your failover.
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